1. Field of the Invention
The present invention relates to adjustable throw crank shafts and eccentric shafts as a means for varying the stroke of an interconnected components of mechanisms.
Many mechanical devices rely on crank shafts or eccentric shafts, hereafter referred to as eccentrics, interconnected to various types of motion mechanisms to transform rotary motion to reciprocating motion or reciprocating motion to rotary motion. An example of the first type of transformation is a typical gasoline engine wherein the reciprocating motion is linear, the power being transmitted from the piston through the connecting rod to cause the eccentric to rotate. An example of the second type of transformation, also in a linear device, is an air compressor. In this case the power is transmitted from the eccentric through a connecting rod to the piston. A washing machine is an example of a device which could use the mechanism to transform rotary motion to reciprocating angular motion.
On occasion there is a need to adjust the throw of the eccentric of such a mechanism, in order to change the magnitude of reciprocation. The vast majority of eccentrics have fixed throws, and therefore will not meet this need. Many devices have been suggested to provide adjustable throw eccentrics. Kirschmann (3,798,996) teaches an outer crank sleeve mounted on two spaced apart eccentric collar assemblies. By rotating the collar assemblies the eccentric is adjusted. This device is somewhat complicated and therefore expensive to produce in small quantities. It requires the mechanism to be stopped during the adjustment, and is difficult to adjust accurately. Oliver (4,538,336) teaches a simpler device which would be somewhat less expensive to produce than Kirschmann's device, but also requires the device to be stopped during adjustment, and is even more difficult to adjust accurately. Antonenko (3,375,730) and Seeger (3,470,823) teach devices similar to Oliver's, and has the same limitations. Dulger (4,235,130) teaches the use of cam shaped grooves in the eccentric. The connecting rod attaches to these grooves. Adjustment is by means of actuating a worm gear assembly. While the device can be adjusted while running, it still has the problems of relatively expensive production, and difficulty in accurate adjustments. Simonton (3,436,988) teaches a device similar to those of Oliver and Seeger, but with the addition of a jack screw attached to a gearing mechanism to provide adjustability while running. While it meets the requirement of adjustability during running, it is also difficult to adjust accurately, and would be relatively expensive to produce in small quantities. Eagan (4,261,228) teaches a device in which a spherical journal is mounted to a pivoted bracket. The adjustment is made by means of a mechanism comprised of a hand knob and shaft, a threaded gear, thrust bearings, and a fork. The device can be adjusted while running, however the adjustment is difficult to make accurately, and because of its complicated design, would be relatively expensive to produce in small quantities. Booth (3,106,105) teaches an adjustable eccentric wherein the adjustment is provided by the axial movement of a canted slide. This device can also be adjusted while running, however, because of its complicated design, it would also be relatively expensive to produce in small quantities. Moret et al (4,326,314) teaches a canted journal which can be moved axially in relation to the bearing, thereby adjusting the stroke. This design is specifically applied to a powered tooth brush, which would be manufactured in large quantities. This design would also be relatively expensive to produce in small quantities.